Thioglycol esters



Patented Nov THVIOGLYCOL ESTERS Maxwell A. Pollack, Denvllle, N. J.,asslgnor to (E. F. Drew & Co. Inc., poration of Delaware New York, N.Y., a cor- No Drawing. Application July 14, 1945,

Serial No. 605,199

6 Claims. (Cl. 260 -399) The present invention is directed'to thioglycolesters and more particularly to compounds of this character which findutility in various commercial applications.

In the prior art, various esters of'thiodiglycol and otherthiopolyglycols have been known. For

instance, esters of such glycols with lower fatty' acids having from 1to 4 carbon atoms have been proposed as plasticizers for syntheticrubber. Also, esters of certain fatty acids having from 7 to 9 carbonatoms in the molecule with thiodlglycol have been proposed as softeningagents for incorporation into certain vinyl ester resins and the like.None of the esters heretofore proposed have had any extendedapplication, most likely because the properties of such esters did notrender them suitable or superior for the intended purposes.

The present invention is intended and adapted to provide esters ofthioglycols which have excellent properties for incorporation in varioussynthetic resinous or similar materials such as the vinyl resins andsynthetic rubbers.

It is also among the objects of the present invention to provide partialesters of thioglycols which shall have desirable properties for use asemulsifiers, dispersing agents, wetting agents and the like.

In practicing the present invention, I may provide a thiomonoglycolwherein the alkyl radical has'a small number of carbon atoms preferablywithin the range of 2 to 6 carbon atoms. The thiomonoglycol alsoincludes thiomonoglycerol and like substances. Compounds of this typeare reacted with fatty acids having from 6 to 18 carbon atoms. Thereaction products may be of single acids with the glycol or mixtures ofsuch acids may be reacted therewith. Several such mixtures have beenfound especially suitable such as a fraction of coconut oil fatty acidswherein lauric acid is the principal constituent and a differentfraction of coconut oil fatty acids wherein caprylic acid is the majorconstituent. 'In general, the acids which may be used for reaction withthe thiomonoglycol include n-caproic acid, 2-ethy-1butyric acid,enanthic, capyrylic, 2-ethylhexoic, pelargonic, capric, lauric,myristic, palmitic, stearic, oleic, linoleic, linolenic, etc. Mixturesof these acids may be used, and in particular, mixtures of acids such asare obtained from natural fats and oils or from various fractionsthereof, may be used. Compounds of this character are excellentplasticizers for synthetic resins, cellulose products, rubbers, etc.,while par tiallyesterified compounds of this character are .ucts havingespecially valuable properties.

quite useful in industry and might be utilized as wetting agents,dispersing agents, emulsifiers and detergents.

- The present invention also contemplates certain esters of thethiopolyglycols. It has been found that the higher fatty acids havingfrom 12 to 18 carbon atoms and higher, namely, those acids which arefound in natural glyceride oils and synthetic acids having the samenumbers of carbon atoms, may be reacted to give substantially neutralesters wherein two molecules of the acid and one molecule of thethiopolyglycol react. Also, mixtures of such acids may be used andparticularly a mixture containing lauric acid as the major constituenthas been found to give prod- In general, esters of this type areexcellent softening agents or plasticizers for synthetic resins, rubbersand the like. A relatively small amount of such softening agent iscapable of imparting desirable characteristics to the substances beingplasticized.

The following are typical substances which may be utilized in thepresent invention:

are listed above as typical substances to be used in making the estersof the present invention, they oxide in methyl alcohol.

illustrate the large numbers thereof which are available. Still othersubstances of the general character may be used in place thereof-in thedescribed reactions. The polyglycols may contain other elements andconfigurations than those specifically named herein which will allow thedescribed reactions to proceed.

The esters may be prepared in a variety of ways, including direct'esteriflcation of the thioglycols with the desired fatty acid ormixture of acids, by reaction of the thioglycols with fatty acidchlorides or anhydrides, by ester interchange between other fatty acidesters and thioglycols, or in the case of thiodiglycol also by directreaction between p,p'-dichlorodiethyl sulfide (mustard gas) and thesalts of the fatty acids.

The following examples illustrate methods of preparation and applicationof these plasticizers.

Example I A mixture is made of 1 mol. of thiodiglycol with 2 mols. of amixture of fatty acids obtained by fractionat'lng the free fatty acidsof coconut oil having the following composition:

. Per cent Lauric a 63 Myristlc a 25 Palmitic acid 12 then refined bymethods known in the art including a washing with an aqueous alkalisolution, the product being a low melting solid. If necessary ordesirable, the product may be bleached and otherwise further refined.The product has the formula ROCHzCI-IzSCHzCHzOR, wherein R is a lauric,myristic or palmitic acid radical.

Exaimple II One mol. of thiomonoglycol, which is prepared from ethylenechlorohydrin and sodium hydrosulphide, is mixed with 1 mol. of afraction obtained from the distillation of the free fatty acids ofcoconut oil having the following composition:

Per cent Capric acid 40 Caprylic flf'id 54 Caproic acid 6 Theesterlflcation reaction is conducted in approximately the manner setforth in Example I, the product being a neutral light-colored oil. Theproduct has the formula RSCHzCI-IzOI-I, whereinR. is a capric, caprylicor caproic acid radical.

Example III A mixture is made of 2 mols. of the methyl ester of lauricacid and 1 mol. of thiotriglycol. To this is added a solution of 0.1% ofsodium'meth- The mixture is heated to a temperature of about 200 C.under a short fractionation column. As the reaction proceeds, methylalcohol is formed and is continuously removed in the vapor state throughthe column. The heating is continued until no more methyl alcohol isreleased, indicating the end of the esterifying reaction. The residue isneutralizedwith aqueous hydrochloric acid, washed twice with water anddried. The final product is a clear slightly yellow solid having a freefatty acid value below 0.3 calculated as oleic acid. This product givesstrong highly elastic compositions when blended with a vinyl chlorideand vinylidene chloride copolymer in a proportion of about 30%. Suchcomposition retains its flexibility down to very low temperatures. Theproduct has the formula RDCHZCHZSCHL'C'HQOCHiCHZOR, wherein R is alauric acid radical.

Example IV The product of Example III is blended in a proportion of 30parts per with polyvinyl butyral on a hot roll, giving a strong,homogeneous sheet, from which thin sections were cut and incorporatedbetween glass sheets to give a safety glass composition. Thiscomposition is much stronger and impact-resistant than glass sheets ofequal thickness, and on breaking, the broken pieces of glass adheredstrongly to the interlayer. This feature is extremely desirable for theautomotive and airplane industries. Moreover, these properties areretained over a wide range of temperature, "as, for example, from F. to-20 0., thus giving stable compositions which would be useful in hotclimates as well as in cold areas.

Example V Ten parts ofthe diester of thiomonoethylene glycol with capricacid is incorporated as the sole plasticizer in a tire tread stock basedon GR-S synthetic rubber (copolymerized butadiene and Example VI Amonoester of thiodiglycol and iauric acid is prepared by mixing onemol.of each of these materials and heating in a current of carbondioxide until the theoretical amount of water has been liberated. Theresulting low-melting solid is an excellent emulsifying agent.

Example VII A monoester of monothioglycerol and stearic acid is producedby essentially the same procedure as in Example VI. The solid product isvery use- 0 ful as a blending and emulsifying agent in the formulationof cosmetic creams, waxes, powders, pastes, etc.

Esters of the thiomonoglycol withnatural and synthetic caproic andcaprylic acids give excellent plasticizing action in polyvinyl butyralcompositions such as are used as interlayers for safety glass.

Similar. esters, but of the higher molecular weight acids, such as thedilaurate, or mixed caprate-laurate, with thioglycols have proved to beexcellent plasticizers for the synthetic rubbers, including butadienecopolymers with styrene, acrylonitrile, etc., polyisobutylene,polychloro-butadiene, etc. In general, these plasticizers have asurprisingly high degree of compatibility with the aforementionedresins, and small percentages produce large softening actions.

Further, it has been found that these softening actions are maintaineddown to very low temperatures (40 to 50 degrees below zero, Fabien--polyalkylene polysulphides,

heit), so that the plasticized compositions have a wide range ofutility. In addition, their high boiling points give them excellentstability in compositions which may be exposed to high temperatures andwhere low volatility is of prime importance, as in fabric coatings wherethe fabrics are exposed to tropical heat and direct sunshine, etc.

Monoesters of these and other acids with the mentioned alcohols are alsoexcellent plasticizers, but generally are somewhat more volatile thanthe diesters, and preferably should be used where this greatervolatility will not be a serious drawback.

In addition, many of these monoesters have demonstrated excellentemulsifying and blending properties which make them useful in manyapplications, including wetting agents, dispersing agents for oils inaqueous systems, detergents, cosmetics, polishes, protective waxes,insecticides, textile finishes, lubricants, etc.

Although the invention has been described by the use of a number ofspecific examples, the invention is not limited thereby but suchexamples are to be considered as illustrative of the breadth of theinvention. While several specific mixtures of acids which are reactedwith the thioglycols have been named, various other mixtures may-also beprovided and the acids may be synthetic as well as natural. Mixtures maybe made of acids having even and odd numbers of carbon atoms and ingeneral it is preferable that such 6 These and other changes in thedetails of the invention may be made within the spirit thereof, thescope of which is to be broadly construed and not to be limited exceptby the character of the claims appended hereto.

I claim:

1. An ester of a thioglycol having at least one sulphhydryl group with ahigher fatty acid having from 12 to 18 carbon atoms.

2. An ester of a thioglycol ether having at least one sulphhydryl groupwith a higher fatty acid having from 12 to 18 carbon atoms.

3. An ester of a thioglycol thio-ether having at least one sulphhydrylgroup with a higher fatty acid having from 12 to 18 carbon atoms.

4. An ester of a thioglycol having at least one sulphhydryl group with amixture of at least two higher fatty acids having from 12 to 18 carbonatoms.

5. An ester of a thioglycol having at least one sulphhydryl group with amixture of at least two higher fatty acids having from 12 to 18 carbonatoms, said mixture containing a major proportion of lauric acid and theremainder being myristic and palmitic acids.

6. An ester of a thioglycol having at least one sulphhydryl and onehydroxyl group with a higher fatty acid having from 12 to 18 carbonatoms. MAXWELL A. POLLACK.

REFERENCES CITED Kranzlein et al July 18, 1922 Hentrich et a1 Aug. 22,1944 Number

